The overall objectives of these investigations are to define more precisely the manner in which immunologic reactions may cause damage to the cornea, and to relate these immunopathologic processes to problems of clinical importance. Our research goals for the coming year include further development of the local graft-versus-host model for corneal endothelial destruction: a) to better establish the dose-response relationship between sensitized lymphocytes and degree of target cell destruction; b) to define more precisely the cells involved in the destructive process, and whether several cell types may be needed to accomplish pock formation; c) to determine by immunosuppresion of the recipient host whether the donor lymphoid cells may act alone or need some contribution from host inflammatory cells; and d) to examine more closely by electron microscopy whether our earlier impression is correct that lymphoid cells may actually enter into the target endothelial cell and in some cases effect its destruction from within.